The invention provides an optical device where the deviation of a pixel is restrained by simple constitution, and a projector equipped with the optical device. A plurality of optical modulators 35R, 35G and 35B are respectively opposed to the incident surfaces Sr, Sg and Sb of a cross dichroic prism 38, and liquid crystal light valves 32R, 32G and 32B that are a portion of components are respectively supported on supporting substrates 40 and 41 provided on the upper surface and the lower surface of the cross dichroic prism 38 through a fixed frame 44. Thus, in the optical device 30, even whenthe thermal expansion coefficients of the supporting substrates 40 and 41 differ from that of the cross dichroic prism 38, dimensional change in a surface direction on the supporting substrate is caused in a direction orthogonal to the alignment direction of the optical modulators 35R, 35G and 35B.